Electrical relay.



S. G. BROWN.

ELECTRICAL RELAY.

APPLICATION FILED 001.14, Isla.

1,175,699. Patented Mar. 14, 1916.

www' A rt/QM 2% M i grwz/w UNITED STATES PATENT OFFICE.

SIDNEY GEORGE BRCWN, OF LONDON, ENGLAND.

ELECTRICAL RELAY.

Application filed October 14, 1913.

To all whom it may concern.'

Be it known that I, SIDNEY GEORGE BROWN, a subject of the King of Great Britain, residing at l Great Winchester street, in the city and county of London, England, have invented certain new and useful Improvements in Electrical Relays, of which the following is a specification.

This invention relates to variable resistance of electrical relays for wireless telegraph apparatus, the main object of the invention being to make certain improvements in such relays, which will, while giving great sensitiveness, allow of ready adjustment of the contact and maintain it in satisfactoryY condition without requiring much attention. Y

The construction of relay which it is my object to improve is a single point contact relay in which one contact element is carried on a balanced lever while the other is on` a vibrating reed controlled by the receiving coil or coils.` The balance of this lever must be adjusted with great delicacy as the chief object of the invention is to'get an extremely sensitive relay which will enable very small currents to bedetected. The balance is adjusted by means of small weights screwing to and fro on the lever and a solenoid or electromagnet device supplied adjustably with current and acting on an extension of the lever to give the desired pressure between the contacts. The balance may be made so as just to separate the contacts when the small steady but adjustable current overcomes the balance and brings the contacts together. The solenoid may be placed around an oil cup which forms a dashpot for the core to prevent mechanical vvibrations affecting the lever. It is necessary to make the pivotal support of the lever very sensitive and I propose in one form to provide it with knife edge or point supports; or in another form to mount it on a small spring strip suspension which can be twisted to vary the pressure between the contacts.

In order that the invention may be clearly understood and readily carried into e'ect the same will be described more fully with reference to the accompanying drawings, in which Figure 1 is a side elevation and Fig. 2 aV Specication of Letters Patent.

Patented `mar. ist, MMS.

serial No. 795,113.

tail views illustrating the electromagnetic method of controlling the pressure of the relay contact; and Fig. 5 is a detail ci' amodiiied electromagnetic device suitable for use in relays employed on board ship or in circumstances in which they are liable to mechanical disturbance; Fig. 6 is a diagram or typical circuits with which the relay is associated. n

A is a contact lever carrying the point Contact a made of practically non-oxidizable metal or alloy.

B is the vibrating reed carrying the carbon Contact 7) and under the control of the electromagnets C (one or" which is shown in Fig.r l) which are in the detector or receiving circuit (Fig. 6) and are mounted on the two ends of the horse shoe magnet o. The reed B is secured by the screw VZ/ between the two supports b2 on which the fixed end of the reed bears, the reed being reduced in thickness at its middle portion 3 to give the desired exibility and allow of sufficient vibration of the free end under the action of the electromagncts C.

D is the base of the apparatus carrying the case (Z which completely incloses the relay mechanism and protects it as far as possible from external disturbances. The base D also carries the terminals Z and Z2 for the external connections to the magnets C and the relay reed B and lever A.

f E, E are solenoids or electromagnets, shown in Figs. 3, 4 and 5 for regulating the pressure between the contacts i and t.

The lever A is provided. in the constructions shown in Figs. l and 2, with two rearwardly extending balancing arms a carried by a cross bar z2 to which the spring suspension strip F is connected at each end, as shown clearly in Fig. 2. This suspension is made of great delicacy and is carried between the two small standards f. One end of the suspension strip is fixed but the other end is connected to an adjusting head f which is turned so as to twist the strip until the desired pressure between the contacts a and Z) is obtained. A small screw f2 may be provided to secure the end ot the strip.

In the electromagnetic method of controlling the pressure of the lever A, which may be used with the spring strip suspension already described or with the point or knife edge pivot at supported on the standards f3 the solenoids E oF Figs. 8 and si. act

nad

in the saine direction'and exert an upward pull on the vertical members or cores L3 of the balancing lever arms a. The balance inay be so adjusted that the required contact pressure is given entirely by the electromagnetic pull upon the cores cts. The solexioids E are excited from any suitable source of constant current, for example, the battery 2/ in the circuit Y of Fig. 6, and the current and consequently the contact pressure of the relay are controlled by any simple form or rheostat y (Fig. 6) or equivalent device external to the case, so that the adjustment can be made 'without access to the apparatus. Gr, as already mentioned, the device may be made self regulating by placing the soleiioids or electromagnets E in the local circuit (as indicated diagrammatically by the connection e in Fig. 3) through the contacts t and t and by making the members a, of magnetized steel so Ypolarized that the pressure ot the contacts varies with, but inversely to the normal undisturbed relay current. The balance of the lever A lis adjusted by the small weight o5 screwing to and fro on a screw threaded part of the lever. The weight is adjusted until the 1ever is just balanced on its pivot or slightly overbalanced so as to break contact and the electromagnetic device is entirely relied on vt-o give the contact pressure. The point or edge bearings for the lever A are of c0n-l siderable importance tor the eiiicient working of the relay as they provide a rigid but practically frictionless support. The lever A and reed B are included in any suitable local circuit, such as the telephone circuit Z of F ig. 6.

in the modification shown in Fig. 5 the lever A is provided with the adjustablel balancing weight afl and Vtwo vertical core arms a6 project downwardly into the solenoids E', which are wound to act in opposite directions and are on opposite 'sides of the knife edges a4. The solenoids are on cups e supplied with thick oil into which the arms c@ project so as to form a daslipot device which reduces the danger of .irregular movements due to mechanical causes. The axis of support of the lever should pass through the center of gravity so that mechanical vibrations transmitted through tlie knife edges have no tendency to turn the lever. The lever support may be mounted upon the reed carrying the lower relay contact.

Wvith regard to the carbon contact if this be made from crystalline carbon a single large ycrystal is cut-and ground to give the desired surface. The action 'of the relay with a carbon contact of this type is very sharp as the hard surface'causes a rebound of the metal point and brings-about a large change of resistance at each disturbance. The disk contact is made, as in microphones from powdered carbon with binding material, which is baked, ground and polished. With a disk contact it may be found advantageous to make the contact between the metal and carbon in oil. TWhen the relay is used as a telephone relay for wireless telegraphy l may use a dry cell .e in the local circuit Z (Fig. 6), giving a pressure of about lilvolts, a variable resistance z being provided in the circuit. The relay may however be used to work a Siphon 0r other recorder.

lVhat l claim and desire to secure by Letters Patent of the Uni-ted States is 1. In electrical relay apparatus a wireless detector circuit, al single point contact relay com risin@F -a balanced lever. a vibratl. b

ing reed, meeting contact pieces on the said lever and reed, an electromagnet in the detector circuit controlling the said reed, and a local relay circuit including the lever land reed.

2. 'In a single point contact relay a 'vibrating reed, a balanced lever, meeting con tact pieces Von the said re'edand lever anda point or edge bearing for the balanced lever around Vwhich it can rock.

3. In a single point Contact relay a balanced lever, a' vibrating reed, meeting contact pieces on the said lever and reed and an electromagnet device acting on the said lever and controlling the pressure between the lever and reed contacts.

l. In ay single point contact relay a vibrating reed, a balanced lever, meeting Contact pieces on the said lever and reed, two solenoids, an adjustable current Vsupplied for the solenoids and two core arms on the said lever, extending into the said solenoids.

5. ln a single point contactrelay, a local., relay circuit, fa vibrating reed, a balanced 'lever co'perating with the reed in the said circuit, a permanently magnetized extension on the said lever and a solenoid placed in Vthe local circuit into which solenoid the`4 said magnetized extension projects.

6. In a single point Contact relay, a screw threaded balanced lever carrying one Contact, a balance weight adapted to' screw to and fro on the said lever and a vibrating Genies of this patent may be obtained for five-cents nach, by addressing lthe Commissioner of Patents, Washington, D. C.

.115 reed carrying the second contact,a receivingVY` 

